Question

(a) 5x – [y – {7x – (y – x)}]​

Answer 1

Answer:

x+y

5

−

x−y

2

=−1 .................. (1)

x+y

15

+

x−y

7

=10 ................. (2)

Let

x+y

1

=u and

x−y

1

=v

Then equation (1) and (2) becomes,

5u−2v=−1 ................. (3)

15u+7v=10 ...............(4)

Multiply equation (3) with 3,

15u−6v=−3 ................. (5)

Now subtract the above result from equation (4),

7v+6v=10+3

13v=13

v=1

⇒x−y=1 ................... (6)

From equation (3),

5u=−1+2v

5u=−1+2

5u=1

u=

5

1⇒x+y=5 ................... (7)

Adding (6) and (7) , we get,

2x=6

x=3

From equation (7),

y=5−x

y=5−3

y=2

Answer 2

Answer:

13x - 2y

Step-by-step explanation:

5x - [y-{7x-(y-x)}]

5x - [y - {7x - y + x}

5x - [y - 7x + y -x ]

5x - [2y - 8x]

5x - 2y + 8x

13x - 2y